1. Field of the Invention
The invention relates to gripping tools, specifically pliers that are designed to be clamped firmly in place on some type of workpiece. More particularly the invention comprises a locking pliers tool featuring an improved dual action driver handle that allows the user to quickly and ergonomically squeeze the tools handle forward or rearward to respectively lock or release the tool's jaws.
2. Discussion of the Background
Articles or components are often held in place, sometimes for a long time, by pliers-type devices. A pliers-type gripping tool is considered the most favourable tool for this work, especially, if the jaw width can be made to be variable and a sure grip and release can be effected with a minimum of effort. These tools comprise a fixed handle, a movable jaw that responds to pressure squeezing on the handles. When the user wishes to grab an object such as an alligator clip, a pipe fitting, an engine part or even a barbecue fork left in the coals too long, he or she squeezes the handle and opens the jaws. Then one engages the object and twists the piston to effect a lock of the tool in place.
Normally these kind of toggle locking handle tools have a two-tonged handle, three fixed pivot points and a knurled adjusting knob that protrudes out of the end of the top most handle. One squeezes the handles together, pushes the jaws on to the workpiece, twists the handle until desired pressure is achieved and the tool is secured.
Locking pliers heretofore proposed for such use are of a single action design, opening and closing at the rear of the tool only, proving awkward to grasp and are disproportionate to the user's hand. Problems occur if the user decides to lessen the pressure temporarily or to remove the tool entirely. What one must do is reach in with both hands and twist the knurled piston follower while holding the handles. Once the tool is loosened sufficiently to disengage it then a squeezing action with one, sometimes both hands finally does free it. All this is difficult and at times impossible when the workpiece is confined or, if the pliers were attached with extreme force by strong hands and fingers. Such tools may also rely on complicated lock release mechanisms which divert the user's full grasp from the tool.
Whether it's vise grip or lock grip, these hand tools go by a variety of names and they let the user perform a wide range of jobs around the home, workshop, construction project etc. One sees them employed in clamping applications, welding applications, grinding tasks or in simple recreational activities. When the user cannot hold larger, more awkward shapes' he resorts to this type of curved jaw, force multiplying tool. It will lock and release instantly.
With so much demand for these tools inventors have attempted to solve the problems of a tension releasing and applying hand tool. The following patented references show various solutions to the challenge of engaging a workpiece with the worker's own minimal use of force, attaching and releasing successfully all with the tight confines of a workspace typically no larger than an engine compartment, a crawlspace beneath a shed or around the pipes under a kitchen sink.
U.S. Pat. No. 5,056,385 to Peterson teaches a five point pivot toggle-locking hand tool mechanism with a compound toggle linkage action. Peterson purports to have invented a tool which gives the user a mechanical advantage and a force multiplying four point power line.
U.S. Pat. No. 5,460,065 to Balmer teaches a toggle mechanism between the operating handles which allow for a camming action as the user opens or closes the handles and varies the points of contact of the jaws on the workpiece. Such a tool still only gives a craftsperson an inexact jaw lock position based on his or her ability to manipulate the compound link as the camming surfaces slide around a circular bore. This adjusting process is potentially endless and not convenient when the user cannot see what he or she is doing or cannot actually estimate the size of the workpiece itself.
U.S. Pat. No. 2,838,973 to Peterson shows a complex locking wrench device. For a user to operate this system, they must master a tension spring, web, a hook, a handle and an actuating lever cum web. Peterson does provide force multiplying pressure on the gripping jaws, but the tool is complicated to operate and not recommended for novices.
U.S. Pat. No. 3,354,759 is simply described by inventor Cook as vise grip pliers. Cook provides a button on the top handle in place of the traditional knurled edge screw treaded locking piston that normally put pressure on the jaws when the object is to be clamped. The Cook reference surpasses the other locking wrench inventions for complexity. So many levers must be simultaneously pressed, and levers engaged as that top button is pushed that the tool cannot be termed convenient.
U.S. Pat. No. 6,626,070 to Peperkorn features a quick release toggle locking mechanism. This compound toggle link controls the degree to which the tool can open. Opening the tool to obtain the so-called “snap” feel reveals a problem. This invention does not solve the problems a user encounters in trying to open and close the tool within a confined space and at the same time not dropping the pliers as he relaxes his grip to flick the handle open or clamp the jaws closed.
Wooster, U.S. Pat. No. 6,012,361 discloses a lockable pliers wrench. To operate the Wooster wrench one rotates a knurled screw to open or close the conventional jaws. This is known but Wooster's release lever is nested within the upper handle and the user closes the jaws with almost a cocking movement of the link into an over-center position. Wooster uses a release lever in the lower handle to open the jaws. This is inconvenient in that one has to move a hand from what was a secure grip to the end of the lower handle where the release lever is located. Wooster provides no provision for quick locking/unlocking of the jaws. Further, this set of pliers device can't be operated at will with a sure one-grip motion.